package com.wanxi.test;

public class DateTypeChange {

    public static void main(String[] args) {

        byte num1 = 3;
        byte num2 = 4;
        byte num3 = (byte) (num1 + num2);//数据类型强制转化
        System.out.println(num3);


        byte num4 = 3 + 4;
        System.out.println(num4);//3和4是两个常量, Java存在常量优化机制，编译成功


    }

}
